Metal, and particularly copper, pipes are often joined by a thermal joining operation, such as a high temperature, open flame welding, brazing or soldering operation. In certain instances, a first section of metal pipe is joined to a second section of metal pipe by a short length of connector pipe, such as an elbow joint, to alter the direction of the flow inside the continuous conduit formed by connecting the pipes. In other instances, a valve that can be alternately opened and closed to permit and prevent flow through a pipe is inserted at a convenient location along the pipe. Regardless, the joining operation is typically utilized to join the connector pipe or valve to the pipe at each point, known as a "joint," where the connector pipe or valve intersects the pipe.
During a thermal joining operation, it is high desirable to confine the thermal energy generated by the thermal joining apparatus to an area immediately adjacent the joint. Otherwise, thermal energy transferred along the pipe can cause damage to the connector pipe or valve, or to other pipe joints. In the case of welding a valve between a break in a pipe, the heat transferred along the pipe can destroy the seals or gaskets, which are usually made of rubber, inside the valve. Similarly, the heat generated by the thermal joining apparatus can distort the metal pipe, or can distort metal components within the pipe or within a valve positioned inside the pipe. In addition, the heat transferred along the pipe away from the joint can possibly ignite combustible structure or materials in the vicinity of the joint.
Various means and methods are known for suppressing the transfer of heat generated by an high temperature, open flame joining operation. U.S. Pat. No. 3,430,686 to Parkison et al. discloses a heat shield which is wrapped around a pipe between the area of the joint and the area to be protected from the heat generated by the joining operation. The heat shield includes a micro-encapsulated coolant, such as oil or water, which is released during the joining operation as the microcapsules melt. The heat generated by the joining operation is transferred to the coolant, thus causing the coolant to evaporate and dissipate the heat in the form of steam. Such heat shields, however, are ineffective for suppressing the transfer of heat generated by a high temperature, open flame joining operation because a significant portion of the heat is nevertheless transferred along the pipe beyond the heat shield.
U.S. Pat. No. 3,593,409 to Silverstein discloses a paste, or putty, made of a water swollen bentonite clay. The putty is applied to the pipe between the area of the joint and the area to be protected during the joining operation. The putty absorbs and dissipates a portion of the thermal energy. Unfortunately, the putty is not capable of absorbing and dissipating the heat typically generated during a high temperature, open flame joining operation. Further, the putty melts easily, thus forming molten droplets which may come in contact with structure or materials in the vicinity of the joint, and must be reapplied to the pipe often during the thermal joining operation.
In a particular thermal joining operation, the need to greatly suppress the heat transferred along a pipe is extremely important. The risk of fire is significantly increased when a break or leak in an existing run of pipe embedded in a wall is repaired. A small portion of the wall is typically removed to expose the damaged or leaking section of the pipe between the vertical studs of the wall. The opening in the wall is made as small as possible to limit the extent of the subsequent repair to the wall. As a result, the operator of the thermal joining apparatus, for example a welding torch, must work in a confined area. Accordingly, it is generally not possible for the operator to utilize a heat shield that is cumbersome or produces an off-gas.
Although there is typically sufficient space to apply a heat suppressant putty to the pipe, molten droplets of the putty are produced when the putty melts which may adhere to the structure and materials behind the wall. Typically, it can be expected that there will be insulation or other combustible building materials in the area adjacent the joint. If left unprotected, these materials may ignite during the thermal joining operation and cause a fire. More alarming, the materials may smolder for several hours before igniting. It is not uncommon for a fire to ignite several hours after a plumbing repair has been completed and the opening in the wall has been covered. Naturally, a fire which starts behind a wall can cause substantial damage to the infrastructure of the building before being detected.
For these reasons, and others, it is highly desirable to suppress the thermal energy that is transferred along a pipe when a joint is formed by a thermal joining operation, such as a high temperature, an open flame welding, brazing or soldering operation. Although many means for suppressing the heat generated by a high temperature joining operation have been proposed, none reduces the transfer of thermal energy along a pipe sufficiently to prevent damage to connector pipes, valves and other pipe joints, and to prevent the possibility that structure or materials in the vicinity of the joint may ignite.
Accordingly, it is a principle object of the present invention to provide a means for suppressing the thermal energy generated in the area of a pipe joint during a thermal joining operation from transferring along the pipe to structure and materials in the vicinity of the joint.
It is another, and more particular, object of the invention to provide a means for conveniently and effectively reducing the transfer of heat along a pipe that is generated during a high temperature, open flame welding, brazing or soldering operation.
It is another, and still more particular, object of the invention to provide a heat suppressing wrap for greatly reducing the transfer of heat along a metal pipe behind a wall that is generated during a thermal joining operation, such as a high temperature, open flame welding, brazing or soldering operation.